Pressurized beverages, such as beer, are produced in a manner that the beverage contains a certain amount of dissolved gas, typically carbon dioxide (CO2). While a certain amount of dissolved CO2 occurs naturally in the beer brewing and fermentation process, most large commercial breweries dissolve additional CO2 into their product. Adding additional CO2 serves two main purposes for the commercial breweries. First, from a quality control standpoint, all the beer produced can be modified to contain the same amount of CO2. Second, the additional CO2 gives the beer a more effervescent quality, which is perceived by the consumer as having better crispness and flavor.
Beer produced by most major breweries contains between 10 and 15 psi (68950 and 103425 Newtons per square meter) of dissolved CO2. Since atmospheric levels of CO2 are substantially smaller, beer has a tendency to release some of its dissolved CO2 when exposed to the ambient atmosphere. Due to the complex chemical makeup of beer, foam tends to form when this dissolved CO2 comes out of solution.
Additional parameters contributing to the amount of foam occurring in beer include temperature and turbulence. The physical properties of liquids dictate that the higher the liquid temperature, the lower its capacity for dissolved gasses. Thus, the greater the temperature of beer, the greater the tendency for its dissolved gasses to come out of solution and the greater the tendency of the beer to foam. Turbulence and other forms of agitation produce regions of sudden, extreme pressure variation within the beer that cause CO2 to come out of solution in the form of foam.
While much of the beer produced by the major commercial breweries tends to be packaged in bottles and cans, a large volume of beer is also packaged in large, sealed containers known as kegs. Kegs are reusable and refillable aluminum containers that allow for efficient, sanitary handling, storage and dispensing of typically 15.5 gallons (58.7 liters) of beer. Beer packaged into kegs, called keg beer, is commonly served at bars, taverns, night clubs, stadiums, festivals and large parties.
Dispensing keg beer into open containers for consumption requires specialized equipment. The beer dispensing faucet (commonly called the beer tap) comprises a valve and a spout for controlling and directing the flow of beer into an open container. Beer often foams as it is dispensed from conventional faucets. One cause of such foaming is simply the pressure differential between CO2 dissolved in the beer and CO2 present in the ambient atmosphere; CO2 will naturally be released from the beer when the beer is exposed to the atmosphere. Another cause of such foaming is the turbulent nature by which beer is dispensed from conventional faucets; even when dispensed carefully, beer splashes onto the walls and bottom of the container and foam results.
A small amount of foam is often desirable. Beer that has not been stored properly often loses its dissolved CO2 to the atmosphere and is considered to be flat. Thus, a small amount of foam indicates to the consumer that the beer is fresh. Additionally, beer marketers have been successful in portraying the perfect container of beer as possessing a frothy layer of foam. On the other hand, too much foam is undesirable to the consumer and the beverage vendor. Since foam fills up a container with CO2 instead of with liquid beer, excessive amounts of foam leave the consumer dissatisfied, often to the point of requesting a new container be served. Knowing this, vendors are left with two choices. They can partially fill a container, wait for the foam to dissipate and then add additional beer, a time-consuming process. Alternatively, they can pour out excess foam as they are filling the container, wasting beer in the process.
Since excessive foaming is problematic for both the consumer and the vendor, attempts have been made to design beer dispensing systems that are installed and configured in a manner that ideally achieves optimal amounts of foam in the dispensing process. In addition to maintaining the beer at a constant, cold temperature throughout the dispensing process, conventional beer dispensing systems are configured to pour beer at a slow enough flow rate that beer exits the faucet at a velocity that does not cause foaming when the beer impacts the container.
Conventional systems are optimized for a flow rate of one U.S. gallon (3.785 liters) per minute. While such a flow rate is suitable for most low-volume dispensing applications, there are many situations in which it would be beneficial for both the vendor and the consumer if beer could be dispensed more quickly while still maintaining optimal amounts of foam. At busy bars, taverns, festivals, large parties and stadiums, consumers often must wait in long lines before being served. Under these circumstances, it would be desirable for both the vendor and the consumer for beer to be dispensed more quickly.
Previous beer dispensing systems have been designed to dispense beer more quickly than the standard one U.S. gallon per minute flow rate. One drawback with these systems is that they typically employ elaborate electronic control mechanisms, making them expensive to manufacture and maintain. Additionally, some of these systems employ the use of a reservoir near the point of the faucet making the devices large and difficult to clean. Moreover, the retrofit of such devices onto existing bar tops can be difficult and expensive.